Automatic liquid drain mechanism



AUTOMATIC LIQUID DRAIN MECHANISM Filed May 2, 1966 5a 56 46 au lo. /VV y ZN 555 A 63j l' 3M@ Va j f 74 70 52 h`75 369395 (80 5g FB az man 22K j (7@ Bl:-

Jeff/v 5. /Vf $45 United States Patent O 3,419,034 AUTOMATIC LIQUID DRAIN MECHANISM Atlee S. Hart, 22140 Stratford, Oak Park, Mich. 48237 Filed May 2, 1966, Ser. No. 546,899 3 Claims. (Cl. 137-172) ABSTRACT OF THE DISCLOSURE A device for automatically drawing an impurity from a tank such as water from a fuel oil tank. A threaded fitting screwed into a drain opening in the tank carries a solenoid operated drain valve and an electrical probe which extends through the itting into the tank. An electrical circuit actuates the valve to drain the impurity in in response to sensing of the impurity by an uninsulated tip portion of the probe located in the tank.

This invention relates to means for automatically draining a relatively heavy 1iquid impurity such as water from a vessel containing a lighter liquid such as diesel oil. In one embodiment the vessel may be the bowl of a lter arranged in the fuel line of a diesel engine to remove solid and liquid impurities from the oil. The porosity of the lter element is such as to trap the larger water molecules in the bowl, thus preventing the water from harming the fuel injectors. To preclude build up of water in the bowl such as might allow it to immerse and flow through the iilter element it is common practice to periodically drain ot the accumulated water through a bottom drain opening in the filter bowl.

An object of the present invention is to provide means for automatically exhausting a heavy liquid impurity from a vessel containing a lighter liquid without human intervention or assistance.

A further object is to provide a liquid exhausing means which includes an electrically-operated liquid valve and a relatively simple low cost electrical control circuit for said valve.

Another object is to provide a valve and control circuit package which can be installed on and removed from the liquid vessel as a unit.

A further object is to provide a control circuit which includes but one electrical probe responsive to the level of liquid impurity in the vessel.

A still further object is to provide a control circuit wherein the exhausting operation is initiated by a single liquid level probe, and terminated by charging up a capacitor during the liquid exhaust period.

In the drawings:

FIG. 1 is a view partly sectional and partly schematic, showing a valve and control circuit embodying the invention.

FIG. 2 is a schematic view showing a control circuit used in a second form of the invention.

FIG. 3 is a reduced view showing a physical packaging of the FIG. 1 control circuitry.

FIG. l shows the lower wall portion of a filter bowl or vessel for a conventional diesel fuel oil system used to supply oil to a diesel engine. Arranged in the illustrated wall portion is a threaded drain opening 12 which conventionally receives a manually turnable drain plug to permit periodic removal of water impurity which may have accumulated in the vessel. As shown in FIG. 1, the drain plug has been replaced by a tubular litting 14 having wrench ats 16 on its outer surface. The lower end of fitting 14 defines a valve seat 18 which is normally closed by a rubber-capped magnetic valve element plunger 20 slideably retained within a nonmagnetic tubular guide 22 carried by brass connector element 24. A compression coil spring 26 normally holds plunger 20 up in its illustrated closed position.

Patented Dec. 31, 1968 Telescoped onto guide 22 are two tubular magnetic pole pieces 28 extending inwardly from the flanges of a C-shaped magnetic frame 30` Contained within the frame is a conventional epoxy-encapsulated electric coil 32 having the usual spade terminals (not shown) for connection to lead wires 34 and 36. Retention of frame 30 and coil 32 on guide tube 22 may be readily accomplished by a spring clip 38.

In the FIG. l arrangement energization of coil 32 causes plunger 20 to be drawn down to an open floating position centered between pole pieces 28. Coil energization is normally initiated by an electrical signal generated when the water impurity builds up to a level suflicient to contact the uninsulated tip 40 of the probe wire 42. Until the water level rises above insulation 44 there is normally no signal and no solenoid energization.

Wire 42 is connected to a control circuit which includes a source of positive voltage 46, three transistors 48, 50 and 52, and a capacitor 54. One path for current tiow can be traced from source 46 through line 56, junction 58, line 60, the emitter-base circuit of transistor 48, line 62, the emitter-base circuit of transistor 50, lines 64 and 66, wire 42, the water impurity, and the grounded wall 10 of the lter bowl. This current flow turns on transistors 48 and 50, and produces an amplified usable current through a circuit comprising source 46, line 56, junction 58, line 60, the emitter-collector circuit of transistor 48, line 68, junction 70, line 72, junction 74, lead 34, coil 32, lead 36 and line 76 to ground. Current iiow through coil 32 draws the hexagonal armature plunger 20 downwardly, thus permitting gravity flow of water past seat 18, around the plunger, and out to atmosphere.

Initially part of the current at junction 70 flows through a circuit comprising line 78, capacitor 54, line the base-emitter circuit of transistor 52, and line 82 to ground. Transistor 52 is thus turned on to provide a circuit in parallel with the circuit going from junction `65 through line 66 and probe 42. The action is such that probe 42 turns the three transistors on; as soon as the water level drops below the exposed tip 40 the on condition is maintained by the collector-emitter circuit of transistor 52. The on condition is limited timewise by the R-C time constant of capacitor S4. When the capacitor is sufficiently charged (after for example one second, more or less depending on the capacitor of the liquid vessel and anticipated rate of water exhaustion) transistor 52 is turned olir to thus turn oft" transistors 50 and 48, and deenergize coil 32.

If the capacitor 54 should unexpectedly charge up before the water level drops below the exposed tip 40 the transistors 48 and 50 will remain turned on by the current ow through wire 42. Coil 32 will therefore remain energized as long as necessary to exhaust the accumulated water to a level :below tip 40. During the next charging cycle the water will be exhausted to a level determined by the R-C constant for capacitor 54.

A control circuit employing two insulated wire probes is shown in FIG. 2. In this circuit, when the Water level rises to level 80 the circuit is turned on; when the level drops to level 82 the circuit is turned olf. The turn-on signal goes through a circuit comprising source 46, line 84, junction 86, line 88, the emitter-base circuit of transistor 90, line 92, the emitter-base circuit of transistor 94, line 96, the emitter-base circuit of transistor 98, line 100, and insulated probe 102 having an exposed tip at level 80. An ampliiied usable current is taken through a circuit comprising source 46, line 84, junction 86, line 88, the emitter-collector circuit of transistor 90, line 104, coil 32, and line 106 to ground. The liquid valve thus opens to drain water from the vessel.

After the water level drops below the tip of probe 102 the turn-on signal is maintained by probe 108. Thus,

the current in line 100 finds an alternate path through diode 110, junction 112, line 114 containing resistance 116, probe 108, the liquid, and the grounded vessel.

Part of the current in line 104 proceeds through a circuit comprising junction 136, line 138, the base-emitter circuit of transistor 134, and ground line 140. Transistor 134 thus turns on to reduce the potential at junction 122. The purpose in thus reducing the junction 122 potential is to reverse bias diode 124 such that the current through probe 108 must be the emitter-base current of transistor 98. Thus, transistors 98, 92, 90 and 134 are held on as the liquid drops from level 80 to level 82. When the water drops below level 82, the signal through transistors 90, 94 and 98 is interrupted, thus effecting deenergization of coil 32 and transistor 134.

During the next rise in water level it is necessary that the transistors remain off until level 80 is reached; to preclude turn-on of the transistor when level 82 is reached, transistor 98 is biased by a circuit comprising junction 86, line 118, resistance 120, junction 122, diode 124, junction 126, high resistance 128, junction 130, and portion 132 of line 100. In the ofi condition of transistor 134 junction 122 is substantially at the source 46 voltage so that the potential at the base of transistor 98 is suiciently high that transistor 98 is in an oit state; this state occurs even though the water level rises above the tip of probe 108. As the Water reaches level 80 transistors 90, 94 and 96 are turned on by the aforementioned circuit through probe 102; the cycle thus repeats itself to maintain the water level between levels 80 and 82.

Advantageously the control circuitry of FIGS. l or 2 can be packaged directly on the valve assembly, as shown for example in FIG. 3. The package can include a printed circuit board 142 having the various components (such as the transistors, diodes, resistance and capacitor) on its left face and printed circuits on its right face, said components having the usual terminals projecting through openings in the board for electrical connection with the printed circuits. The insulated probe wire 42 can also be extended through one of the board openings and suitably soldered to the circuitry.

Solenoid 32 may be of the nylon or epoxy encapsulated type which is commonly provided with a lateral boss 144 and two parallel spade terminals 146, only one of which is visible in FIG. 3. The printed circuit board can be provided with a pair of slot-like openings for receiving the spade terminals, which are then preferably soldered to the right face of the board to mount same on the solenoid. A cover (not shown) may be provided around the board to shield the electrical connections from rough usage. Power for the unit must of course be brought in by a cable (not shown) coming from the diesel engine ignition system.

Preferably the entire control package is supported solely by iitting 16, which permits easy installation and/ or removal in existing Vehicles, as by mere replacement of the conventional drain plug. Some variation in detail may of course be resorted to while still practicing the invention as recited in the appended claims.

I claim:

1. In combination: a liquid vessel adapted to contain a relatively light nonelectrolyte liquid and a relatively heavy electrolyte liquid impurity, said vessel having a threaded drain opening in its bottom wall for draining away the electrolyte impurity; a threaded tubular iitting threaded into said drain opening; insulated electrical probe means extending through the passage deiined by the fitting, said probe means having uninsulated tip means located beyond the iitting so as to be within the vessel liquid; a voltage source connected to said probe means; an electrically-operated liquid valve carried solely by said tubular fitting; said valve including a valve element normally closing the passage, and a solenoid electrically connected with the voltage source and probe means to move the valve element to an open position when the tip means becomes immersed in the electrolyte impurity.

2. The combination of claim 1 and further comprising an amplifier for the signal passing from the voltage source through the tip means, and means connecting the output of the amplifier to the solenoid; said amplifier and connecting means being mounted solely on the valve whereby the entire assembly of fitting, valve, ampliiier and connecting means can be installed on and removed from the liquid vessel as a unit.

3. The combination of claim 1 wherein the probe means consists of a single probe element contacting the vessel liquid.

References Cited UNITED STATES PATENTS 2,295,097 9/1942 Waugh 137-392 X 2,508,132 5/1950 Aikman 137-195 2,564,873 8/1951 Wright 137-187 2,573,172 10/1951 Ennis 137-172 2,806,896 9/1957 Streuber 137-172 X 3,088,592 5/1963 Clark 137-172 X 3,131,335 4/1964 Berglund 137-392 X 3,187,949 6/1965 Mangel 222-76 X ALAN COI-IAN, Primary Examiner.

U.S. Cl. X.R. 137-392. 

